FIG. 1 illustrates a typical current transformer (CT) of the prior art, generally indicated by reference numeral 10. The CT includes a primary winding 14, which carries current from a power source 18 to a load 22, and a secondary winding 26, which receives an induced current from the primary winding 14. The secondary winding 26 is connected to a measuring/monitoring device 30, which could be a protection device such as a circuit breaker, overload relay or other device capable of interpreting an induced current signal received from in the secondary winding 26. If the induced current signal from the secondary winding 26 indicates that current in the primary winding 14 has exceeded a predetermined level the monitoring device 30 can initiate an interruption of current flow in the primary winding 14. In more sophisticated protection devices the monitoring device 30 can include a memory 34 for storing algorithms 38 used by at least one processor 42 to interpret the induced current signal from the secondary winding 26, determine if current flow in the primary winding 14 exceeds the predetermined level and initiate the interruption of current flow in the primary winding 14.
Current transformers, as described above, are widely used in protection systems to monitor load currents. In many applications CTs are placed in areas where the temperature can vary enough to affect the accuracy of the CT. In critical applications where accuracy of the CT is extremely important a temperature sensing device can be installed near the CT to provide local temperature information. The CT monitoring equipment can use the local temperature information to compensate for the temperature's effect on the CT. This requires installing the temperature measuring device and connecting it to the CT monitoring equipment, which adds additional cost for the temperature sensing equipment and its installation. In some instances the CTs are installed inside small enclosures that do not have room for additional sensing devices or in locations that are difficult to access. In these situations the temperature sensing device may not be close enough to the CT to provide accurate local temperature readings that can be used to increase the accuracy of the CT. Therefore, having a temperature sensing device that is actually an integral part of the CT would be beneficial.